1. Field of the Invention
The present invention generally relates to the art of piezoelectric vibrators, more particularly to a haptic feedback apparatus used in an electronic device for providing haptic feedbacks.
2. Description of Related Art
As disclosed in U.S. Pat. No. 7,535,454 B2, portable electronic devices, such as mobile phones, portable GPS navigations, laptop computers, generally have a number of buttons that allow a user to interface with the devices by inputting information. The capabilities of these devices are increasing while the size and weight are decreasing to enhance portability. For example, mobile phones, in addition to their traditional role as voice-communication devices, now include functions traditionally associated with other devices, such as electronic games, PDAs, and digital cameras.
To permit effective interaction with the handheld devices, the handheld devices typically provide visual and aural cues or feedback. In addition to conventional visual and aural feedback, some of these devices attempt to enhance the effectiveness of device feedback by providing tactile cues or feedback. Some devices utilize structural tactile methods. One such example is to provide raised surfaces on the input surface, e.g., a keypad, of the device. Such methods, however, are inherently static and thus cannot offer effective tactile feedback. Generally, a piezoelectric vibrator includes a diaphragm, and a pair of piezoelectric layers separately attached to two sides of the diaphragm. Excessive amplitude of the diaphragm will affect the performance of the piezoelectric vibrator.
Active methods of providing tactile feedback include incorporating a vibrator into the handheld electronic devices. Such a method of providing haptic cues, however, generally vibrates the entire device. Such method or apparatuses are disclosed in U.S. Pat. Nos. 7,535,454 B2, 7,148,875 B2, 6,853,965 B2, 6,429,846 B2, 6,405,158 B2.